Find the number of atoms in 7.6g of sodium phosphide

The formula for sodium phosphide is Na3P, and its molar mass is 3 (22.99) + 30.97 = 99.94 g.

so the number of moles in 7.9g of Na3P is 7.9g * 1 mol/99.94g = 0.079 moles

there are 6.022*10^23 atoms in a mole, so the answer is 6.022*10^23 atoms/mol * 0.079 moles = 48*10^21 atoms